The present invention relates to endoscopic surgical instruments, and more particularly to instruments known as end effectors which may include cutters or scissors, graspers and dissectors which are useful in laparoscopic or endoscopic procedures. The surgical instruments made according to the present invention are monopolar.
The use of heat for the cauterization of bleeding wounds dates back for centuries. More recently, the use of radio frequency (RF) electrical current traveling through a portion of the body has been widely used to stop bleeding. The RF energy cauterizes the blood by heating the blood proteins to a temperature where those proteins congeal similarly to the process involved in the cooking of egg whites. RF energy is preferred because its frequency is above that which could otherwise cause neuromuscular stimulation. The most frequently used modes of RF cauterization are monopolar and bipolar coagulation.
In monopolar coagulation, an active electrode is applied to a bleeding site and electrical current flows from the electrode through the patient""s body to a return electrode which may be a conductive plate in electrical contact with a large surface area of the patient""s body such as the buttocks or thigh. One technique in which the monopolar mode may be employed involves fulguration which is the use of a spark or arc from the active electrode to the tissue.
Bipolar devices include both the active and return electrodes. Thus the electrical current flows down the surgical instrument to the active electrode and typically crosses a space on the order of millimeters, or shorter, to the return electrode and returns through the surgical device.
Endoscopic surgical instruments, such as the monopolar electrosurgical end effectors, are often used in laparoscopic surgery, which is most commonly employed for cholecystectomies (gall bladder surgeries), hysterectomies, appendectomies, and hernia repair. These surgeries are generally initiated with the introduction of a Veress needle into the patient""s abdominal cavity. The Veress needle has a stylet which permits the introduction of gas into the abdominal cavity. After the Veress needle is properly inserted, it is connected to a gas source and the abdominal cavity is insufflated to an approximate abdominal pressure of 15 mm Hg. By insufflating the abdominal cavity, a pneumoperitoneum is created separating the wall of the body cavity from the internal organs. A surgical trocar is then used to puncture the body cavity. The piercing tip or obturator of the trocar is inserted through the cannula or sheath and the cannula partially enters the body cavity through the incision made by the trocar. The obturator can then be removed from the cannula and an elongated endoscope or camera may be inserted through the cannula to view the body cavity, or surgical instruments such as monopolar electrosurgical end effectors according to the present invention, may be inserted to perform the desired procedure.
Frequently an operation using trocars will require three or four punctures so that separate cannulas are available for the variety of surgical instruments which may be required to complete a particular procedure. Additionally, electrosurgical instruments, such as this design for monopolar end effectors, may be utilized in open surgery techniques as well.
Other techniques for coagulation have a variety of shortcomings. While non-contact positioning of a laser may be useful in some instances, the laser has no way of holding a bleeding vessel and is not used on large bleeders. Laser based cauterization instruments remain expensive and unsuitable for tissue dissection techniques other than cauterization, such as blunt dissection or sharp dissection. Laser cauterization instruments suffer from the additional shortcomings of difficulty controlling the depth of penetration of the laser energy and that non-contact positioning of a laser can permit the laser beam to reflect off of other instruments and cause damage to surrounding tissue.
Monopolar end effectors may be useful in particular applications in which bi-polar instruments are not a preferred option due to technical restraints. Additionally, some of the prior art monopolar instruments may have predictability problems in current flow due to the use of two conducting blades acting as one electrode in conjunction with a separate electrode. Furthermore, the operator may be limited by particular end effector designs which do not allow for a more precise channeling of RF energy.
Presently, monopolar effector designs, especially monopolar scissors, utilize a pair of relatively large metal blades, at least one of which also functions as an electrode. Even if only one blade were utilized as an electrode during an energized procedure, the other blade is also active and may act as a conductor and attract or conduct current to tissues. Current will generally follow the path of least resistence. The presence of a second active blade in close proximity to an energized electrode provides an attractive current path. This is not a desirous result for a user as this effectively increases the surface area of the active electrode. It is believed that the larger the exposed area of the active electrode, the larger chance that a surgeon may inadvertently conduct current into unintended portions of tissue. Conducting current into unintended tissue may damage tissue and result in collateral damage.
The present invention incorporates two blades: (1) an active blade and (2) an insulated and/or inactive blade. With both scissors blades closed, the inactive blade may be used as a shield while the active blade is utilized as an electrode. The insulated blade may protect tissue including organs when using the active electrode. The inactive blade may, or may not, contact tissue during the use of an active electrode.
Monopolar effectors have been found to be effective at a technique known as spray fulguration which allows for current to be jumped to the tissue without contact of the effector with the tissue. Other techniques useful to operators may, or may not, involve contact of the monopolar electrode with a particular tissue. The invention described herein overcomes common monopolar end effector shortcomings and may effectively reduce the number of surgical instruments required for a given procedure.
It is therefore an object of the invention to provide an improved surgical instrument with monopolar end effectors.
It is an additional object of the invention to provide an instrument having monopolar end effectors wherein one end effector has an active conducting portion and the other effector is inactive.
It is a further object to pass current through the conducting portion of the first end effector to effect coagulation caused by the RF energy at a location desired by the operator.
It is yet a further object of the invention to provide a monopolar instrument which utilizes RF energy more precisely to cauterize a particular tissue portion and thereby minimize damage to other tissue.
Another object of the invention is to provide the ability to energize and de-energize the RF energy at the electrode.
Another object of the invention is to provide a conductive portion of a blade of an end effector and a second non-active blade.
It is still a further object of the invention to allow the operator to utilize the effectors to dissect spread, or move tissue independent of coagulation procedures.
Still another object is the minimization of lateral damage to surrounding tissue as current is conducted from a single blade to the tissue.
Additionally, an advantage of the invention is the ability to use the non-active blade to protect particular tissue from inadvertent exposure to coagulation current while utilizing the active electrode.
These and other objects of the invention are accomplished by the utilization of one blade having a current conduit connected to a conductive portion. This active blade may be utilized to cut tissue in conjunction with a second non-active blade.